Abstract: The forefoot portion of a shoe bottom includes at least one independent open air cavity composed by complementing concave arcs found in the lower midsole and upper midsole. The upper midsole includes at least one ventilation hole for the passage of air to and from the wearer's foot. During compression of the shoe bottom, caused by the wearer's foot, the open air cavity forces air through the ventilation hole, and through the insole hole introducing air into the shoe interior.

Abstract: In a shoe bottom heel portion, an upper midsole of a heel portion includes a central bulge and peripherally arranged pillars, a lower midsole includes a central mound opposing the bulge and peripherally arranged sockets receiving said pillars, and a thin, stiff shank extending rearward from the arch portion of the shoe bottom is bonded to the central bulge and to the central mound. Cavities are formed surrounding the central mound and openings are formed between the contacts. Through bending as well as compression, the upper and lower midsole and the shank cooperate to absorb impact. Optionally, the contacts are simplified and flattened. Optionally, the shank is omitted. Optionally, either of the mound and the bulge is omitted or substituted for the other.